motor life

Did the Skyhawk motor piston look like this?



That is what happens when you don't put enough oil in the gas, in this case no no oil in 2 days, or try to run a new motor over half an hour wide open with no rest.

Please note that assessment is based on no pictures or other info other than a 'CNS' carb which ships with SKyhawk kits.

Be it not enough oil, beating it to death out of the box, or just leaning the air/fuel mix so much you burn it up you may want to explain exactly what you have and how you are 'adjusting' it because it is pretty obvious you are doing something really REALLY wrong to burn up 3 motors when most good ones last years.

Running your motor with the air filter removed will alter your air/fuel mix, make it go lean which will make your motor run hot and possibly cause damage. Best thing to do is get your motor setup with the air filter and everything nice and sealed all the way from the air filter to the exhaust and then tune the carb to run right.

As for fuel mix, I generally do 20:1 for the first gallon, then 24:1 for the second gallon, then 32:1 from then on using conventional 2-stroke oil (NOT the marine type), but thats just my take on ratios. You don't want to spend time tuning the carb before you are running the final 32:1 mix because the mix will effect the tuning.

You've gone through a LOT of motors man, my skyhawk is still rolling with about 2,500 miles on it so far. I would think with that many dead motors you should be able to piece one together that will run?

Which brings me around to asking what exactly is wrong with your motors? You said you "killed the compression", so I am assuming they die with a no compression scenario? The first thing I would ask you is did you check the head torque? Maybe the head just came loose and you lost compression?

hawkeyeinvt said:

Yes I've checked the head tourque I've changed the rings I've done all I can think of spark gas so all that is left is compression. I think it was the air filter problem.

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You're making it kinda hard to help you, I mean, do you have a motor to fix or not?
The first thing I would say is break in you motor well, with the proper gas mix and do not ride it wide open throttle for more than short bursts until you've burned through two gallons of break in mix. Second, run with the air filter ON. Third, add an inline fuel filter. Fourth, make sure your head stays torqued...

As for the compression, it should be pretty easy to feel the compression when you let out the clutch and/or feel the change if there is a loss of compression. Is this the case? Are the cylinder walls scored? Pistons burned? rings trashed? If you have a cylinder that isn't scored, good rings, a good head gasket and a properly torqued head with spark plug installed you should get compression unless there is excessive wear, it seems none of your motors ran long enough to achieve excessive wear...
Post pictures of what you got going on and maybe we can help you, otherwise, I just got an email that skyhawk motor only are on sale for $109/48cc and $119/66cc with free shipping at gas bike, if you want to just burn up another one....

Note, also, that a 2-stroke sends whatever comes in the carb down into the cases first - did you crunch the main bearings?

No air filter = dirty and lean fuel mixture = no go engine. You've got to have an air filter. With the amount of money you spent on engines, you could have bought a 4 stroke kit and had money in the bank and free time on your hands.

Here's a few guides to help you setup your next 2 stroke and keep it running:

https://docs.google.com/document/d/1GcesQihc7-mm3hJGf7UPiqOaRXZ8ekUT99QUZq2qXXE/edit
https://docs.google.com/document/d/1aBeJuoS--VQWwXysc07rpscTUbPzgc93xjiQBgsyFjc/edit
http://www.grubeeinc.com/USA/2 cycle engine trouble shooting guide.html

Good Luck,

Chris
AKA: BigBlue

for many folks 'docs.google' doesn't display - is there another source for those?

hawkeyeinvt said:

Ok i have gone through 3 motors and am on my 4 i think i know what happened to them but am not sure. i believe i have killed the compression because i had a cns carb and the blue air filter fell off it made it run better and so i left it off, but i think that having the filter off killed the motor. they all lasted about a month and a half each. i drive bout 20 mins to work each way like 8 miles one way. 5 days a week. i dont believe the motor should have worn out so quickly. if anybody could help me it would be greatly appreciated.

thank you!

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those kits are a hit and miss with quality. I have heard of people getting a couple thousand miles out of them and then i hear of people going through 4 or 5 engines just a couple months. I would be sure to keep and air filter on it. and always make sure your running the correct amount of oil in the gas. I run mine a little richer than the kit calls for just to be safe. The extra lube isn't going to hurt anything. Im talking about just a hair richer than called for. Dont over do it. I run a bumblebeebolton and i use 3 ounces of oil to the gallon. Thats around a 40:1 which is to lean for your skyhawk I believe its an 25:1 ratio on that kit..Good luck!